Marine instruments such as two way radios, depth sounders, Global Positioning Systems (GPS), autopilots as well as components of stereo sound systems frequently are mounted at the control position of smaller boats and vessels so that they can be viewed and controlled by the pilot.
Although many of these instruments are intended to be waterproof it is still desirable and necessary to protect the face of the instruments from rainwater and sea spray. This necessitates a movable cover which must give access to the instrument controls and must protect the instrument from spray or rain when use of the controls is not required and at the same time make the instrument visible